The invention applies in particular but not exclusively to coupling two heavy long motors together vertically. This applies to motor pump assemblies for pumping in oil wells, for example. In such a case, generally three motors are coupled together one above the other. The bodies are coupled together by bolted flanges and the shafts are coupled together by splined sleeves. Connectors fitted with pins and sockets supported by insulating parts provide electrical connection. The kinetics of the coupling operation is as follows: contact between shafts and sleeves, contact of the electric connectors and lastly contact of the bodies.
Such kinetics entails the use of detachable auxiliary systems which allow relative angular and axial positioning of the two motors which are to be coupled together.
In the above operational mode, the fragile parts, i.e. the splined shafts and the electric connectors, are coupled together first and therefore there is a danger of damage in the case of faulty handling or of imperfect alignment and further the operation is dangerous since the operation must intervene during the lowering of the upper motor towards the lower motor to suitably position the shafts, faulty operation by the crane operator then being certain to injure the operator's hands.